Livarski vestnik 59/2012 št. 1
Klaus Dilger, Helge Pries, Sebastian Müller
APPLYING REPAIR WELDING TECHNOLOGIES TO STRENGTHEN THE PERFORMANCE OF DIE-CASTING DIES
Zdenka Zovko Brodarac, Tamara Holjevac Grgurić, Faruk Unkić, Katarina Terzić
INFLUENCE OF MICROSTRUCTURAL CHARACTERISTICS ON MECHANICAL PROPERTIES OF AlSi11Cu2(Fe) ALLOY
P. Mrvar, S. Kastelic, M. Petrič, J. Medved
NEW POSSIBILITIES IN COMPLEX COMPONENT MANUFACTURING WITH HIGH PRESSURE DIE CASTING AND JOINING
A. Megušar, B. Rus, P. Mrvar, A. Mahmutović, LTH Ulitki d.o.o., University of Ljubljana, Slovenia
OPTIMIZATION OF THE PRESSURE DIE CASTING PROCESS OF A CARBURETTOR WITH A GREAT DEMAND TO LOOK PERFECT
Klaus Dilger, Helge Pries, Sebastian Müller
APPLYING REPAIR WELDING TECHNOLOGIES TO STRENGTHEN THE PERFORMANCE OF DIE-CASTING DIES
Abstract
Improving the lifetime of a die-casting die is a key factor for the die-casting industry since the lifetime and economic methods to improve the lifetime have a strong influence on the cost effectiveness of the whole die-casting process. Commonly, the lifetime of the die-casting die is reached when the degradation of tool surface either exceeds a critical value for surface quality or even leads to a breakdown of the whole die-casting die due to gross cracking. In the first case, repair welding enables the regeneration of die surface without being confronted with manufacturing a new die-casting die.
The article starts with a brief introduction into the failure modes of die-casting dies. Furthermore, it provides a brief economic assessment of the lifetime, regarding the uptime and downtime criterion. In order to point out the potential and restrictions of repair welding, it is focused on three common methods of repair welding: tungsten inert gas welding (TIG), plasma arc welding (PAW) and laser cladding. The characteristic properties of the welded areas and the most important influence parameters on weld quality are pointed out for each method. In addition, the essential manufacturing steps for a high-quality repair welding are compared to the conventional manufacturing process of die inserts. The article finishes with a summary of the achieved results and provides recommendations for repair welding.
The article starts with a brief introduction into the failure modes of die-casting dies. Furthermore, it provides a brief economic assessment of the lifetime, regarding the uptime and downtime criterion. In order to point out the potential and restrictions of repair welding, it is focused on three common methods of repair welding: tungsten inert gas welding (TIG), plasma arc welding (PAW) and laser cladding. The characteristic properties of the welded areas and the most important influence parameters on weld quality are pointed out for each method. In addition, the essential manufacturing steps for a high-quality repair welding are compared to the conventional manufacturing process of die inserts. The article finishes with a summary of the achieved results and provides recommendations for repair welding.
Zdenka Zovko Brodarac, Tamara Holjevac Grgurić, Faruk Unkić, Katarina Terzić
INFLUENCE OF MICROSTRUCTURAL CHARACTERISTICS ON MECHANICAL PROPERTIES OF AlSi11Cu2(Fe) ALLOY
Abstract
Presence of alloying and trace elements in melt indicate formation of complex intermetallic phases which significantly influence alloy properties development. An AlSi11Cu2(Fe) alloy which belongs to “eutectic” group of alloys indicate high values of mechanical properties and castability in as cast state, responsible for its suitability for high pressure die casting production. Determination of equilibrium phase diagram through thermodynamic modelling and simultaneous thermal analysis enables understanding of solidification sequence. Following microstructural constituents have been identified in AlSi11Cu2(Fe) alloy: αAl, αAl + ßSi, Al5FeSi, Alx(FeMn)ySiz, Al2Cu and AlxMgyCuzSiw. Correlation of microstructure constituents characteristics and phase analysis of AlSi11Cu2(Fe) alloy with tensile strength were investigated in this work. An AlSi11Cu2(Fe) alloy achieves high values of tensile strength in both base and modified melt state. Small difference appeared due to solidification sequence progress. Modified melt indicate better castability at same pouring temperature.
Ključne besede: Al-Si alloy, solidification sequence, microstructure development, tensile strength, castability
Ključne besede: Al-Si alloy, solidification sequence, microstructure development, tensile strength, castability
P. Mrvar, S. Kastelic, M. Petrič, J. Medved
NEW POSSIBILITIES IN COMPLEX COMPONENT MANUFACTURING WITH HIGH PRESSURE DIE CASTING AND JOINING
Abstract
With friction stir welding (FSW) aluminium castings got new dimension in assembling cast parts made from different alloys. The aim is to join parts with different properties in place where these, usually better, properties are required. The heat input transferred in joint with FSW is much smaller compared with conventional fusion welding. Low heat input means that deformation of joint is very small, also the residual stress is smaller. In the recent years research was orientated in FSW of wrought aluminium alloys which are difficult to meld or even non weldable. In this article the temperature distribution of FSW joint of a cast aluminium alloy and pure aluminium is investigated. During joining the temperature was measured with thermocouple and the temperature distribution was calculated with FEM programme Sysweld.
A. Megušar, B. Rus, P. Mrvar, A. Mahmutović, LTH Ulitki d.o.o., University of Ljubljana, Slovenia
OPTIMIZATION OF THE PRESSURE DIE CASTING PROCESS OF A CARBURETTOR WITH A GREAT DEMAND TO LOOK PERFECT
Introduction
LTH Ulitki d.o.o. Company has reached with many purchasers the level of suppliers of very demanding products in recent years, and it achieved the status of developing supplier with at least four significant purchasers. Knowledge, quality and flexibility are the basis of our present competitive advantage and they place us among developing suppliers that are closely connected with purchaser already during the designing and development of prototypes.
Carburettors of aluminium alloy are among important products in the LTH production programme. They are usually mounted in a well visible position in the space of car engine. Therefore these castings must look perfect. Casting must have high-quality surface without any traces of cold shuts, short runs or hot tears.
Due to complex shape of the casting and with changing wall thicknesses from thin-walled to thick-walled sections cold shuts, short runs or hot tears can appear in the casting.
Optimization of the casting process to obtain a product with a great demand to look perfect was done in three ways:
Carburettors of aluminium alloy are among important products in the LTH production programme. They are usually mounted in a well visible position in the space of car engine. Therefore these castings must look perfect. Casting must have high-quality surface without any traces of cold shuts, short runs or hot tears.
Due to complex shape of the casting and with changing wall thicknesses from thin-walled to thick-walled sections cold shuts, short runs or hot tears can appear in the casting.
Optimization of the casting process to obtain a product with a great demand to look perfect was done in three ways:
- By simulation of melt flow and of temperature changes from the holding furnace to the die;
- By optimization of filling the die cavity and improved venting of die;
- By simulation of stresses in the die.